U.S. Pat. Nos. 4,567,365 issued Jul. 1, 1986 and 4,835,832 issued Jun. 6, 1989 to the assignee of the present invention and German patent application publication DE 3346056 A1 published Jul. 19, 1984 disclose various forms of assembled or composite camshafts and methods for their assembly. The U.S. patents involve composite camshafts assembled from individual elements such as cams and journals mounted on a hollow tube by mechanical expansion with a ball or mandrel. The German publication shows a hollow camshaft made up of separate hollow elements connected by friction welding. One embodiment includes lightweight formed sheet metal journals.
U.S. Pat. No. 4,638,683 issued Jan. 27, 1987 discloses composite camshafts having ceramic cam sections connected by interference fitted metallic sleeves. Balls received in shaft dimples and engaging grooves in the sleeves are provided for locating and locking the elements in their desired angular orientations.